Dial type switch with improved leaf spring biased rotatable contact plate

ABSTRACT

The disclosure embodies an electrical switching device wherein elongated, resilient contacts are electrically bridged by an electrically conductive plate affixed to an actuatable shaft and rotate the plate upon its release such that the respective points of contact between the resilient contacts and the plate will differ on subsequent operative cycles.

United States Patent Zopff [451 July 18, 1972 [54] DIAL TYPE SWITCH WITH IMPROVED LEAF SPRING BIASED ROTATABLE CONTACT PLATE [72] Inventor: Thomas E. Zoplf, Grand Rapids, Mich.

[73] Assignee: Burroughs Corporation, Detroit, Mich.

[221 Filed: April 13, 1970 [21] Appl. No; 27,787

[52] US. Cl. ..200/ll G, 200/11 K, 200/166 J, 200/164 511 rm. Cl ..H0lh 1/12,H01h 19/58 [58] Field ofSearch ..200/6 A, 6BC, 6C, 11 EA, 200/11 G, 11 H, 11 J, 11 K, 159 A, 166.1 164, 168

[56] References Cited UNITED STATES PATENTS 1,801,589 4/1931 Critchfield ..200/6 C 1,954,272 4/1934 Taylor ..200/6 A 2,233,944 3/1941 Genda ..200/6 C 3,483,337 12/1969 Johnstone et a1. ..200/6 A 2,828,371 3/1958 Gayler ....200/1 6 B 3,030,460 4/ 1962 Huetten et a1. ...200/11 G 3,121,143 2/1964 Landry et a1 ..200/ll G Primary Examiner-J. R. Scott Attorney-Kenneth L. Miller and Edwin W. Uren [57] ABSTRACT The disclosure embodies an electrical switching device wherein elongated, resilient contacts are electrically bridged by an electrically conductive plate affixed to an actuatable shaft and rotate the plate upon its release such that the respective points of contact between the resilient contacts and the plate will difier on subsequent operative cycles.

5 Chins, 4 Drawing Figures SUMMARY OF THE INVENTION The invention resides in the provision of elongated, resilient contacts to impart a rotation to an electrically bridging contact plate upon its release.

Prior art discloses electrical switching devices wherein electrical contacts are bridged by an electrically conductive plate which is rotatable to change the respective points of contact between the contacts and the bridging plate. Such devices rely either on random forces or on a separate mechanism to rotate the plate. The very nature of random forces make the rotation of the plate unpredictable and unreliable, and separate rotating mechanisms are necessarily costly to manufacture and are subject to failures due to wear and fatigue.

Accordingly, it is an object of this invention to provide an electrical switching device wherein the plate is rotated by forces imparted to the plate upon its release by the contacts, thus reducing the cost and complexity of the device and increasing its useful operating life.

IN THE DRAWINGS FIG. 1 is a plan view, partly broken away, of an electrical switching device embodying features of the invention;

FIG. 2 is a side view of the device of FIG. 1, shown in its normal or rest position the conductive plate in spaced nonbridging relation to the resilient contacts;

FIG. 3 is a view similar to FIG. 2 showing the switching mechanism in its actuated position and further showing the conductive plate in partial cross-section taken along line 3-3 of FIG. 1 and in engaged electrically bridging relation to the resilient contacts; and

FIG. 4 is another plan view of the device to illustrate the position certain parts assume following the actuation of the switch mechanism.

Referring to FIGS. 2 and 3, the electrical switching device includes an electrically insulating support member 10, an electrically conducting contact plate member 12, a first elongated, resilient contact arm or member 14, a second elongated, resilient contact arm or member 16, and an actuatable member 18. The contact plate 12 overlies the support member 10, and the first and second resilient contact members 14 and 16 respectively are attached at one of their ends to the support member and extend toward the contact plate 12. The actuatable member 18 traverses the support member 10 and is affixed to the contact plate 12.

The electrical contact plate 12 is positioned parallel to the upper surface of the support member 10 and is resiliently biased away by a helical plate return spring 20. The fust elongated, resilient contact member 14 is attached at one of its ends to the upper surface of the support member 10 and extends obliquely from the support member 10 toward the contact plate 12. A first terminal 22 is mounted on the end of the first resilient contact 14 attached to the support member 10. The opposite or free end of the first resilient contact 14 is rounded.

The second elongated, resilient contact member 16 is attached at one of its ends to the upper surface of the support member 10 and extends parallel but obliquely opposite to the first resilient contact member 14 away from the support member 10 toward the contact plate 12. A second terminal 24 is mounted on the end of the second resilient contact 16 at- OPERATION With reference to FIG. 2, the device is shown in its normal or rest position. The mechanism may be actuated by moving the actuatable member 18, either manually or by any wellknown reciprocating device such as a solenoid, in a direction to force the contact plate 12 toward the support member 10, compressing the helical plate return spring and distorting the first and second resilient contact members 14 and 16 0 respectively after the contact plate 12 reaches them, as shown tached to the support member 10. The opposite or free end of by FIG. 3. In this position, the contact plate 12 has electrically bridged the resilient contact members I4 and 16.

When the actuatable member is released, the contact plate 12 will be restored to its rest posifion, principally under the influence of the plate return spring 20. The restoring forces of the first and second resilient contacts 14 and 16, due to their oblique orientation with respect to the contact plate 12, have both normal and tangential components. The normal components aid the plate return spring 20 in restoring the contact plate 12 to its rest position. The tangential components impart a rotation to the contact plate 12 such that it will rotate, for example, from the position shown in FIG. 1 to that shown in FIG. 4. This rotation will present different points on the contact plate 12 to the first and second resilient contacts 14 and 16 during the next cycle of operation, thus increasing the functional life of the device.

What is claimed is:

1. An electrical switching device comprising, in combination:

an electrically insulating support member;

an electrically conducting plate member overlying and resiliently biased away from said support member; an actuatable member joined to said plate member for movement in a direction to advance the plate toward the support member and for mounting the plate member for freely rotatable movement in the plane thereof relative to the support member;

at least two similarly shaped elongated resilient contact arms interposed between the plate member and the support member, said contact arms each being attached at one of its ends to said support member and having the other end free and normally spaced apart from the plate member and all extending obliquely with respect to the plane of rotation of the plate member and all facing in the same vertiginous direction about the axis of rotation of the plate member; and

said actuatable member being operable against the resilient bias of said plate member to force the latter into electrical contact with and to distort thereby said contact arms and being releasable to break such contact, the restoring forces of said contact arms cooperating to impart rotation to said plate member relative to said support member upon the release of the actuatable member, thereby presenting difierent points on the plate member to the contact arms for successive cycles of operation of the switching device.

2. An electrical switching device as defined by claim 1 wherein said actuatable member extends centrally between said resilient contact arms.

3. An electrical switching device as defined by claim 1 wherein the free ends of said resilient contact arms are arcuated away from said electrically conducting plate member, whereby a smooth surface is presented for contact therewith.

4. An electrical switching device as defined by claim 1 wherein said actuatable member is slidably guided by and rotatably journaled in said support member.

5. An electrical switching device as defined by claim 1 wherein said electrically conducting plate member is resiliently biased away from said support member by a helical compression spring disposed therebetween, whereby said plate is nonnally held away from the free ends of said contact amis. 

1. An electrical switching device comprising, in combination: an electrically insulating support member; an electrically conducting plate member overlying and resiliently biased away from said support member; an actuatable member joined to said plate member for movement in a direction to advance the plate toward the support member and for mounting the plate member for freely rotatable movement in the plane thereof relative to the support member; at least two similarly shaped elongated resilient contact arms interposed between the plate member and the support member, said contact arms each being attached at one of its ends to said support member and having the other end free and normally spaced apart from the plate member and all extending obliquely with respect to the plane of rotation of the plate member and all facing in the same vertiginous direction about the axis of rotation of the plate member; and said actuatable member being operable against the resilient bias of said plate member to force the latter into electrical contact with and to distort thereby said contact arms and being releasable to break such contact, the restoring forces of said contact arms cooperating to impart rotation to said plate member relative to said support member upon the release of the actuatable member, thereby presenting different points on the plate member to the contact arms for successive cycles of operation of the switching device.
 2. An electrical switching device as defined by claim 1 wherein said actuatable member extends centrally between said resilient contact arms.
 3. An electrical switching device as defined by claim 1 wherein the free ends of said resilient contact arms are arcuated away from said electrically conducting plate member, whereby a smooth surface is presented for contact therewith.
 4. An electrical switching device as defined by claim 1 wherein said actuatable member is slidably guided by and rotatably journaled in said support member.
 5. An electrical switching device as defined by claim 1 wherein said electrically conducting plate member is resiliently biased away from said support member by a helical compression spring disposed therebetween, whereby said plate is normally held away from the free ends of said contact arms. 